The present invention relates to a stent assembly for keeping open body channels, especially the bile duct.
For draining body cavities, it is known to use a stent assembly, wherein a stent acting as a draining tube is introduced in a patient's body on a guiding string. U.S. Pat. No. 4,963,129 describes a stent assembly with a tubular stent for draining the cavity system of the kidneys. This stent is introduced via a guiding string which is withdrawn when the stent has been positioned. Moreover, a so-called pusher hose is pushed over the guiding string. The proximal end of the stent is supported at the distal end of the pusher hose. A coupling means is provided for transmitting not only thrust forces, but also tensile forces from the pusher hose to the stent. The coupling means consists of two complementary parts at the stent and at the pusher hose that mutually embrace each other and are locked by the guiding string passed therethrough such that they cannot be disengaged with the guiding string inserted. Thus, it is possible to position the stent very accurately, it being possible to pull back the stent over some distance before the disengagement.
German Patent DE 42 33 514 C1 describes a ureter catheter also placed over a guiding string, a pusher hose being provided in addition. The catheter and the pusher hose are connected through a disengageable coupling device locked by the guiding string.
A body channel that is especially hard to access is the bile duct. The bile duct leads the bile produced in the liver into the duodenum. At the mouth of the bile duct, a constriction is located that is called papilla or sphincter and functions as a valve. Liquid bile produced in the liver is introduced into the intestines through the bile duct. When the bile duct is clogged, a stent is introduced for keeping it open, the stent being a tubular prosthesis through which the liquid bile is introduced into the intestines. Inserting the stent is generally done with the help of a special endoscope from the distal end of which the stent is pushed out laterally. In doing so, it may happen that the stent is introduced to deep into the bile duct or is displaced after insertion and disappears in the bile duct. Further, it may happen that the stent becomes obstructed after having been placed. In such cases, it is necessary to remove the stent endoscopically or the correct its position.